The high temperature synthesis of transition metal oxo-carboxylate polynuclear complexes

Abstract

Oxo-carboxylate polynuclear complexes contain more than one metal ion bridged by oxo and carboxylate bridges. One method of synthesis for these complexes is the so called high temperature synthesis where a solid precursor is heated at a temperature between 200-500°C. This research has shown that thermal analytical techniques, EGA-MS and TGA, are an effective way of determining the processes that are occurring at different temperatures during the heating. Thermal analysis may also be used to determine the optimal temperature at which to perform the high temperature synthesis. From the thermal analysis of different compounds used in the high temperature synthesis, it is observed that the product is influenced by the carboxylate ligand and the metal ions present in the precursor. Factors such as the anion, solvent of crystallisation or nuclearity of the complex are seen to have no influence on product formation at higher temperatures. It is proposed that a precursor whose corresponding acid of the bridging carboxylate has a low boiling point will require a lower synthesis temperature to form complexes of the same nuclearity and structure than precursors with carboxylate ligands whose acid has a higher boiling point.